The invention relates to a device for monitoring the presence of steps and pallets of an escalator or moving walkway, respectively.
According to prevailing national and international safety regulations, escalators and moving walkways have to be equipped so that they may be automatically stopped as soon as problems arise at critical points.
U.S. Pat. No. 5,526,256 to Sakata et al. teaches a control device for passenger transport installations. A first and second microcomputer are provided. The first microcomputer actively communicates, via actuators, with the safety elements, which are responsible for starting the movement of the passenger transport installation. Data from the actuators are used for starting the passenger transport installation. The second microcomputer monitors the behavior of the safety devices on the basis of incoming signals. In case of a breakdown of one of the microcomputers, the passenger transport installation is not stopped, but the second microcomputer overtakes the function of the first one. This arrangement results in significant risks during the continued operation of the passenger transport installation because the defect has not been eliminated but only transferred.
In the operating state of a passenger transport installation, the step or pallet belt is a main source of problems. If a step or pallet actually breaks or falls out of the return strand, persons standing in the visible area of the escalator may be injured unless the escalator or moving walkway is immediately stopped.
U.S. Pat. No. 5,361,887 to Zaharia et al. teaches a generic device for detecting the irregularity in step frequency. A proximity-sensing initiator, connected to a microprocessor, can detect if some pre-determined features are missing from an escalator step. In case of a missing characteristic feature, the drive of the passenger transport installation is stopped. If the microprocessor would break down, the passenger transport installation will no longer be functional, due to safety reasons. However, such a breakdown would result in the passenger transport installation being out of service for longer than is necessary.
It is an object of the present invention to improve a device for monitoring the presence of steps or pallets of an escalator or moving walkway such that missing steps or pallets are immediately detected, and the escalator or moving walkway drive can be stopped, before the missing or defective part reaches the visible area of the escalator or moving walkway.
It is a further object to provide a new evaluation capability-based criteria that meets current safety regulations and correspond to the norms, and which is still effective when the microprocessor breaks down.
The above and other objects of the invention are achieved by a device for monitoring a presence of steps of an escalator or pallets of a pallet belt of a moving walkway having at least one initiator, which is operative as a function of proximity for producing signals representing a determination of a missing step of the escalator or a pallet of the pallet belt of the moving walkway. The device also includes an evaluation and control unit having at least two processors that are operatively coupled with the at least one initiator for stopping a drive of the escalator or moving walkway in response to the signals from the at least one initiator indicating a determination of a missing step or pallet by the at least one initiator. The at least two processors operate independently from each other, monitor each other, control the signals of the at least one initiator, and exchange with each other status messages about the respective operating state of the at least one initiator and their own operating state within predeterminable time intervals.
According to another aspect of the invention, there is provided a method for monitoring a presence of steps of an escalator or pallets on a pallet belt of a moving walkway. The steps of the method include: sensing a presence of predeterminable, characteristic and recurring feature at a predeterminable place of the step or pallet belt in a contactless manner with at least one initiator that produces signals representing the feature or absence thereof; supplying the signals to an evaluation and control unit comprising at least two processors; processing and comparing the signals in the at least two processors of the evaluation and control unit; monitoring each processor with one of the other processors; and stopping a drive of the escalator or moving walkway when a feature is detected as absent.
According to an exemplary embodiment of the invention, there is provided a device for monitoring the presence of steps of an escalator or pallets of a pallet belt of a moving walkway having at least one initiator arranged in proximity to a reversing area for each direction of the escalator or moving walkway. The initiator is operative as a function of proximity for producing signals representing a determination of a missing step of the escalator or a pallet of the pallet belt of the moving walkway. The device further includes an evaluation and control unit having at least two processors operatively coupled with the at least one initiator for stopping a drive of the escalator or moving walkway in response to the signals from the at least one initiator indicating a determination of a missing step or pallet by the at least one initiator. According to this embodiment, the at least two processors operate independently from each other and control the signals of the at least one initiator.
Thus, the invention enables the contactless detection of missing steps or pallets on the basis of characteristic and always-recurrent features, i.e., features that are present at each step or pallet.
The axel of each step or pallet can, for example, be used as the characteristic feature. The axel usually cooperates with a roller, which rolls on a guide and is thus always arranged on the same level.
Preferably, the initiator(s) is/are positioned in the region of the housing by means of a respectively associated support and is/are directed towards the characteristic feature, for example the bolt of the step or pallet rolls, which are provided outside the drive branch.
For preventing the missing or defective component (step or pallet) from reaching the visible area of the escalator or moving walkway, the initiator(s) is/are preferably provided in the return strand in proximity to the reversing area of the step or pallet belt, so that upon detecting a missing step or pallet, the drive of the escalator or moving walkway can be immediately stopped via the evaluation and control unit.
Usually, it is sufficient to provide the device with a single initiator for each running direction of the escalator or moving walkway. However, if the effective regulations of individual countries prescribe more, i.e. stricter criteria, two initiators placed side by side are used, so that a redundant safety is given.
According to another aspect of the invention, processors, which operate independently from each other and control the signal(s) of the initiator(s), are provided in the region of the evaluation and control unit, which processors preferably monitor each other. The processors are coupled with safety contacts for immediately stopping the drive of the escalator or moving walkway. The processors exchange status messages with each other about the respective operating state of the initiator(s), on the one hand, and their own operating state, on the other hand, within pre-determinable time intervals.
If an initiator breaks down, or if the the processors, which monitor each other, are not in agreement, the drive of the escalator or moving walkway is automatically stopped.
The velocity profiles (normal speed, creep speed) relating to the escalator or moving walkway are stored within the evaluation and control unit, so that the throughput times, which change due to changing velocities, at the initiator(s) can be recognized without any problems by the evaluation and control unit and associated with the respective operating state. For adaptation to different speeds, so-called self-learning programs, such as adaptive speed recognition, autotuning and teach-in methods, can be used.
For maintenance of the escalator or moving walkway, a manual drive of the step or pallet belt via special control elements is provided (driving mode for inspection), so that the safety device can be switched off for this purpose.
The objects of the invention are achieved by means of exemplary embodiments shown in the drawings and described as follows.